Switch



Nov. 22, 193s. P. s. 'BEAR ET A.. 2,137,711.

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SWITCH Filed Nov. l. 1934 2 Sheets-SheetV 2 Patented Nov. 22, 1938 UNITED STATES Appiicaticn November i, 11934, Seriali No. '35@,92'8

t@ Claims.

inis invention relates to switches, and more particuiarly is directed to switclies of the type employed for controlling electric circuits in accordance with temperature or humidity variations, or accordance with any characteristic condition ci the air or surrounding medium in which tie switch structure is disposed.

control switches responsive to expansion contraction oi a thermally-sensitive or humidity-sensitive element, wherein the circuit controlling mechanism comprises a sealed mercury switch of smalti size, it has been customary, in structures with which i am familiar, to mount the switch in such position that the mercury passes from one side of the center of rotation of the switch to the other. Such a structure, operating in this manner, is disclosed in Patent No. ljiifidli, issued June i7, 1930, to Phelan and Hotchkiss. One of the major objections to switch structures oi this type is that the weight of mercury', in passing over the center of rotation from one side of the switch to the other during actuation, causes a shifting of the load on the sensitive actuating member which results in increasing the differential stress necessary to return the switch to its former position. Thus a greater variation in either the temperature or humidity is required to bring the switch back to its original position, which destroys the utility of the control structure in situations where a narrow rrange of temperature differential control is desired. In addition, the shifting of this weight of mercury results in distortion of the sensitive actuating member, and renders the switch inaccurate in operation.

The present invention, in its preferred embodiment, is directed to a switch structure or similar circuit controlling mechanism responsive to temperature or humidity variations, which structure is so mounted with respect to the axis of rotation of the temperature or humidity sensing member that the mercury in the switch or the load on the actuating means is not shifted over the center of rotation asvthe switch is operated. The load upon the actuating member is therefore substantially constant during movement of the member in response to temperature variations, and the actuation of the circuit controlling mechanism from one circuit controlling position to the other is accomplished without producing any undue stress or distortion upon the actuating member. This is of distinct advantage in situations wherein the circuit controlling mechanism is to respond to extremely small changes or variations in temperature or humidity, or where the rate of (Cil. 24Min-139) response of the circuit controlling mechanism with respect to the rate of movement of the sensitive actuating member is to be varied within predetermined limits at the different temperature or humidity ranges to which the switch structure is subjected.

Another object of the present invention is the provision of a switch responsive to either humidity or temperature variations, and which may be adjustably actuated by varying the actuating connection to a helical actuating member, whereby any predetermined lineal length of the actuating helix may be employed in controlling the actuation of the circuit controlling mechanism. By this adjustable connection, the switch will be less rapid in its action when clamped to one of the inner spirals of the helix than when clamped to the outermost spiral, since the extent of movement of the helix per unit variation in temperature or humidity increases progressively outwardly from the center of the helix, the variation in length of each unit portion of the helix being cumulatively passed on toward the free end thereof. In addition, in the present invention the helix is so mounted as to be adjustable as an entirety about its own axis, so that any desired range of temperature or humidity may be controlled thereby, while the rapidity or vresponse or actuation of the circuit controlling means per unit of variation can be adjusted independently at any desired or preselected temperature or humidity diierential.

This adjustability of response produced by the present, construction, together with the means for setting the helix for controlling circuit controlling mechanism at any desired temeprature or humidity differential, provides a device that is capable of operating practically any desired type of control circuit in response to variations in either of these conditions. Such a device finds particular application in the controlcircuits associated with air conditioning systems, refrigerating systems, drying processes and similarly allied fields.

In addition, the present invention provides a circuit controlling mechanism capable of use ln response to the temperatures of stack gases or the like for controlling heating plants, furnaces of all types, and ovens. In such situations, the temperature increase from normal atmospheric temperatures to the relatively high temperatures of the gases in the stack is considerable, and may be in the neighborhood of from three to seven or eight hundred degrees. Any bi-metallic spiral responsive to these temperatures will, during an increase of temperature over this range, make at least two or more complete revolutions in response to temperature increases or decreases. In order to provide for substantial instantaneous actuation of the circuit controlling mechanism upon a relatively small decrease in temperature from the desired high temperature in the stack, we have provided for interconnection of the coil or spiral and a mechanism for actuating the circuit controlling means through an adjustable clamp, with the connection between the circuit controlling mechanism and the actuating means being carried through a magnetic eld and being entirely independent of mechanical connections. This preserves the switch structure against any damage due to the continued rotation of the actuating spiral, and provides a positive control for circuits controlling the operation of the heating means which controls the temperature of the stack gases. The same features of adjustability of response, with respect to the rate of response as compared to the unit variations of temperature, are present in this embodiment of the invention, so that the rate at which the circuit controlling means is actuated per unit temperature variation can be increased or decreased as desired.

Another feature of the present invention resides in the provision of a compact, easily assembled and easily adjustable structure for control purposes, which may be economically produced, and which is positive in operation,

Other objects and advantages of the present invention will appear more fully from the following detailed description, which, taken in connection with the accompanying drawings, will disclose to those skilled in the art the particular construction and operation of a preferred form of our invention.

In the drawings:

Figure 1 is a front elevational view of a thermally responsive mechanism constructed in accordance with the teachings of the present invention;

Figure 2 is an end elevational view of the switch structure shown in Figure l;

Figure 3 is a perspective detail view of the pivoted actuating bar shown in Figure l;

Figure Il is a perspective view of the clamping member;

Figure 5 is a perspective view of the spring clip employed in the construction shown in Figure 1;

Figure 6 is a front elevational view of a humidity responsive circuit controlling mechanism;

Figure '7 is a side elevational view, partly in section, of the structure shown in Figure 6;

Figure 8 is a detail perspective view of the adjustable clip attaching means shown in Figure 7;

Figure 9 is a front elevational view, with the circuit controlling mechanism shown in section, of a thermally responsive mechanism used for controlling the temperatures of stack gases or the like; and

Figure l is a vertical sectional View, taken substantially on the line ID-I of Figure 9.

Referring now in detail to the structure shown in Figures l to 5, inclusive, the mechanism is shown as mounted upon a supporting panel or the like, indicated at i2, which may be provided with any desired or suitable means for securing the same in position upon a wall or similar support within an enclosure, 4duct or the like.

Mounted upon and extending forwardly from the panel is a shaft I3, which shaft is adapted to have mounted thereon a helical bi-metallic or other type of spiral I4, preferably comprising two metals having diierent coeflicients of thermal expansion, which spiral is secured at its inner end to an enlarged collar I carried by the shaft I3 by means of a securing screw I6. It is to be understood that any type of metal spiral responsive to temperature changes may be employed.

The shaft I3 is provided with an extending portion of reduced diameter, shown at Il, which is adapted to extend through the side openings or slots I8 of a supporting member IS pivotally mounted at one end about the shaft II. The member I9 is secured against sliding movement with respect to the shaft by means of the attaching spring clip 20, which clip is provided with a cutaway portion 22 adapted to fit over the extending end of the shaft I1, and to have frictional engagement with the opposite sides of the downturned flange portion 23 of the member I9 to hold the sam'e in relatively predetermined position for rotation about the shaft Il.

Mounted upon the member I9, and shiftable longitudinally with respect thereto, is a spring clip member 24, which is provided with a dat base portion carrying the attaching bolt 25 extending through the longitudinal slot 2I formed in the upper surface of the member I9, and provided with a wing nut 26 threaded thereon for frictionally securing the clip in predetermined position with respect to the slot 2|.

The spring clip 24 is adapted to receive a mercury switch, indicated generally at 21, which mercury switch is preferably of the metal electrode type, as described in detail in our cepending application, Serial No. 745,842, filed Sep-- tember 28, 1934. This switch is provided with a pair of terminal lugs 28 and 23, electrically and mechanically secured to the metallic cup-shaped electrodes of the switch, and having connected thereto the extending terminal conductors 3U and 32, which are secured to suitable terminal posts 33 carried by the panel I2. Preferably, the switch has an outer coating of cellulose acetate or the like disposed over an initial coating of a phenol condensation productr At its outer end, the bar or member I3 is adapted to be clamped to a predetermined spiral of the thermally sensitive element I4 by means of a clamping member 34 shown in detail in Figure 4, having resilient clamping tongues 35 adapted to engage about the opposed flat surfaces of the spiral, and having a channel portion provided with inturned edges 36 for slidably engaging with the member I9.

As shown in dotted lines in Figure 1, the bar or member I9 may be rotated about the shaft I1, and the clamp member 34 may engage the member I4 at a diierent portion of the convolution thereof, the clamp member 34 being moved inwardly into engagement therewith.

It is apparent, therefore, that the clamping member 34 may be adjustably clamped to any predetermined portion of the spiral lying in a horizontal plane extending through the axis of the shaft II, whereby the response or rate of tilting of the switch 21 upon unit variation in temperature may be varied as desired.

The switch 2'l`is preferably symmetrical about its longitudinal axis so that even when supported independing position, as shown in dotted lines in Figure l, it is still operated by movement of the bar member I9 under the influence of the thermally sensitive member I4.

When the switch 21 is disposed in the position shown in full lines in Figure 1, the helix I4, which ls constructed in such manner as to have the metal of greatest expansion on the inside of the helix, will expand under heat, causing bar I9 to swing counter-clockwise, thus opening the x switch 2l. Upon cooling, the reverse action takes place, and the switch is moved to closed position. By releasing the clip engagement at 34 and 20, the bar can be moved longitudinally of itself and clipped to another convolution ci the helix, with the switch 2l still mounted in vertical upright position. The same edects upon increase or decrease of temperature will result.

However, if the bar i9 be g about its axis Il and clamped upon the opposite side oi the shaft, as shown in dotted lines, the switch will be in inverted or depen position. The reverse operation is then produced. The helix, upon er:-

' pending under heat, will move bar M counterclockwlse as before, which, in this case, will close the swltch, while cooling ci memher it will urge bor i9 clockwise, resulting in ope of the switch.

lt will thus be apparent that the same construction can be employed for control of oil burners or the like, fior cple, and the control of refrigerating mechanisms, merely'by preselected positioning of the switch on the bar. The adjustabllity of the helix is admirably suited :for the changing of the control from a heating circuit to a cooling circuit.

It is also to he noted that the spiral of the present construction does not carry the full 1 weight of the switch and its leads, but this weight is supported mainly on the axis Il of shaft I3, independently of the spiral. Thus the free end of the spiral only is required to eect tilting of the switch. By this construction, the switch never sags oli of the spiral center, and does not overload or stress the spiral, which frequently occurred with switches of the prior types. Further, the mercury never passes over the center of the helix, and the strain of pull, as against compression, produced by such shifting of the mercury is eliminated.

It is apparent that with the member 34 clamped in the position shown in full lines in Figure 1, an extremely small increase 4or decrease in temperature will result in movement of the switch member 21, since the unit variation in length of the spiral I4 is cumulatlvely added and its greatest movement will be at the free end thereof. By moving the clamping member 34 inwardly to grip portions o! the spiral inwardly of its outer end, since the rate of movement of that portion of the spiral per unit increase in or decrease of temperature is smaller than the rate of movement at the extreme end of the spiral,

the rate of response or rate of tilting of the` switch member caused by movement oi' the spiral will be decreased, since the spiral will not move as much at a portion clamped, for instance, as shown in dotted lines in Figure l, per unit variation ln temperature as it will move at the outermost portion of the spiral. Thus the switch will remain in unactuated position during a longer temperature variation when the clamp I4 ls moved inwardly toward the center of the spiral and clamped to one of the inner turns of the spiral.

In addition, the shaft Il is provided with an enlarged annular flange, preferably secured to the collar I5, to which is secured a pointer member 4 0, the member 4I having arcuate movement over a scale indicated at 42, and being so connected with respect to the collar member l5 that movement of the pointer 40 will result in rotational movement of the member I4 about the shaft I3, thus resulting in shifting the temperature range over which response of the member i4 is to be effective for actuating the circuit controlling mechanism 2l.

It will therefore be seen that the mechanism shown in Figures l to 5 of the present disclosure provides alswitch which is capable of controlling a circuit at any desired temperature range, as determined by the position of the member 40, and which ls also capable of having its rate of response to unit increases or decreases in temperature adjustably controlled by means of the adjustment of the clamping member 34 with respect to the turns oi the spiral ld. llihese two adjustments provide a switch construction which is capable oi use in practically any situation arising in this particular held, and is applicable for circuit controlling purposes in air conditioning systems, heating or Ventilating systems, refrigeration systems, and the like.

in addition, it is to be noted that the switch 2l is disposed entirely on one side of the shaft i6. Thus the mercury, indicated in dotted lines at d3, will at no time be shifted over or across the axis oi' the shaft il during operation of the switch from one circuit controlling position to the other, and consequently there will he no undue stress or distortion upon the thermally sensitive element M, or a reversalI in stress due to the weight of the mercury passing from one side of the center of rotation to the opposite side. A more accurate and sensitive control of the circuit may thus be effected. if the switch he shifted to the opposite side of the shaft Il, the circuit controllingv positions thereof will be opposite to those shown in Figure 1, whereby either normally open or normally closed control circuits may be employed.

Considering now in detail the embodiment of the invention disclosed in Figures 6, 'l and 8, this particular embodiment is directed to circuit controlling mechanisms responsive to variations in humidity conditions.

The humidity sensitive structure shown in Figure 6 is mounted upon a supporting panel 45, which panel preferably is adapted to t over any suitable type of wall opening, a rear enclosing box-like member 46 being provided for attachment thereto to form a housing within the wall. It is to be understood that any suitable supporting means may be prvlded.

The panel 45 is provided with a shaft extendlng outwardly therefrom, indicated at 41, which kshaft is provided, at its outer end, as indicated at 48, with means for supporting a humidity sensitive element 49. This element is in the form of a coiled helix, and preferably comprises a parchment element that is coated on one side with a natural gumor gelatin, and on the other side is provided with a water-proof or moisture-proof lm of lacquer or varnish. Such an element will respond readily to any changes in the relative humidity of the air with which it is in contact. `While the element has little driving power in this form to move a switch or other mechanical device, it ls quite capable of moving a light-weight shutter or vane to interrupt a light beam.

ithin the housing 46 we provide a photo-electric cell 50 which cell is connected. through the leads 52 to an outlet conduit 53 leading from the housing, whereby the leads 52 are conducted to lill an amplifier or relay circuit for controlling any suitable circuit in response to actuation of the photo-electric cell D.

Extending from the conduit 53 are a second pair of leads 54 which are led through the adjustable bracket 55 and are connected to a suitable light source 56, which may be a small neon lamp or a relatively small voltage light` bulb. The lamp 56 is preferably enclosed within a substantially light-tight housing which is provided with a light opening or projection 51 directed rearwardly toward the panel 45.

Mounted upon the shaft 41 and extending vertically upwardly therefrom is a vane or shutter 58, which is rotatable about the shaft 41, and is provided intermediate its ends with a slot 59, which slot 59 extends longitudinally thereof and is adapted to receive the projecting end 60 of a clamping member 52, shown in detail in Figure 8. The clamping member 62 is adapted to be clamped over any of the respective spirals of the member 49, and engages within the slot 59 for actuating the shutter 58 in accordance with expansion or contraction of the spiral. The shutter preferably has the extending portion 58 providing for maintaining the light shut oif upon a tendency of the helix to over-run its circuit-controlling position.

The shutter 58 is provided with a cutaway surface 63 and an annularly inclined surface G4, the surface 64 being angularly inclined so that its vertical extent is substantially equivalent to the adjustment of temperature ranges between two adjacent spirals of the member 49, whereby any desired adjustment intermediate the ranges between the spirals may be effected.

The bracket 55 comprises a rear supporting plate engaging the rear surface of the panel 41, and a forwardly extending bracket portion 66, which is provided with shoulders 61 bearing against the front surface of the panel 45, the bracket sliding within a slot 88 extending vertically through the panel. The position of the bracket Within the slot is adjusted by means of the thumb-screw 69, which is supported in a suitable bracket carried by the panel 45, and which engages the bracket portion B6, whereby raising or lowering of the bracket 55 may be effected. This adjustment is necessary in order to move the light source 56 into line along the inclined angular surface 64, so that adjustment of they response of the member 58 can be had intermediate the light opening 51 and a tubular opening 12 carried by the bracket member 55 and disposed in alignment with the opening 51. Thus, when the shutter is in the position shown in Figure 7, no light will pass from the light opening 51 through the light tube 12 to the photo-electric cell as long as the vane is interposed therebetween. Thus, upon rotation of the vane due to decreasing relative humidity, the shutter is moved to the left, as viewed in Figure 6, about shaft 41, and permits light to pass from the light opening 51 through light tube 12 to the photo-electric cell, causing actuation of the same to control the circuit for adding more humidity to the air, if the device should be employed in an air condition system. Thereupon the increase in humidity of -the air would result in expansion of the member 49 and consequent movement of the shutter 58 across the path of the light between the light opening 51 ^nd the member 12. This would shut off the light to the photo-electric cell, and consequently would cut oiI the means supplying moisture to the air in contact with the device. It is thus apparent that accurate control of the relative humidity in the air may be obtained. In addition, an adjustable pointer 13 is provided which is capable of rotating the shaft 41, the lower end of the pointer 13 being movable over a scale 14 preferably calibrated in terms of relative humidity. This, in effect, rotates the entire spiral 48, and thus changes the setting of the device for different humidity ranges. The pointer is rotated by means of the pinion engaging in a suitable rack 15 formed in the rear surface of member 45. A projecting thumb screw 11 is provided for rotating the pinion, the screw 11 being laterally movable in a slot 18. Suitable bracket means 19 connect the pointer 13 to the pinion shaft for conjoint movement therewith. Obviously such an adjustment might be provided for the embodiment of the invention shown in Figures 1 to 5 without departing from the scope of the present invention. Further, varying the position of the clamping device 82 with respect to the spirals, that is, moving it toward the innermost spiral, or outwardly, results in progressively decreasing or increasing the rate at which the vane member responds to unit humidity variation. This adjustment corresponds to the adjustment described in connection with the thermally sensitive circuit controlling structure shown in Figure l to 5.

It is to be noted that the bracket 55 is movable vertically to position .the light 56 in any desired position along the edge 64 of thejvane 58. This, in a large degree, compensates for the increase in rate of movement of the vane due to positioning member 62 in engagement with one of the inner spirals. Thus the bracket 55 may be moved along the inclined edge B4 in accordance with the position of the clamp 62 to provide any desired adjustment of the rate of response of the vane to unit variation in moisture or humidity.

It is thus apparent in this embodiment of the invention that adjustment can be made of the setting of the entire device with respect to a desired range of relative humidity to be maintained in the room, for example, if the device is used in an air conditioning system, and that individual adjustment of the device for varying its rates of response per unit variation in relative humidity can be made bvmoving the clamping member G2 outwardly or inwardly with respect to the center of thespiral and clamping it to different spirals in the member 49.

In addition, by adjustment of the thumbscrew B9, additional minute variations can be made along the angular surface 64 for varying the rate of response in a: range lying intermediate two of the spirals.

Referring now to the embodiment of the invention shown in Figures 9 and 10 which discloses the invention as specifically applied to means for controlling the temperature of stack gases or the like, although it is to be understood that the mechanism is suitable for other uses, we have provided a supporting base 80, which base is adapted to be provided with two supporting standards 82 and 83 having projecting bearing portions 84 and 85, the bearing portion 84 preferably being adjustable. A mercury switch of the axially rotatable type, as disclosed in detail in our above mentioned copending application, is supported for rotation between the bearings 84 and 85. This switch comprises a pair of cupshaped metal electrodes 86 and 81, separated by a ceramic spacing member 88 having an upwardly extending separator 89 for dividing the two bodies of mercury 90 upon opposite sides of the separator 89. Upon rotation of the switch about the bearings, the separator 89 is moved to such a position that the mercury can flow together, effecting contact between the two metallic electrodes 86 and 81, and thereby completing a circuit between the conductors 92 and 93.

For details of construction of this particular type of switch, reference is to be had to our copending application, in which the switch and its operating characteristics are described in detail.

Mounted about the switch, substantially centrally thereof, is a bracket member 94, provided at its upper end with a supporting flange adapted to carry a magnetically responsive member 95 extending forwardly thereof.

The base 80 is also provided with another arm @l which supports a shaft 99 carrying a spirally coiled thermally sensitive member thereon. The thermally sensitive member |00 may be of the same form as the member I4 shown in Figure 1, and is disposed for expansion and contraction about the fixed shaft 99.

Clamped to any desired coil of the thermally sensitive member is a clamping member |02, corresponding to the clamping member 02 of Figure 8, which is adapted to engage in a vertical slot |03 formed in an arm |04 carried by a second shaft |05 mounted upon the extending arm portion |06 formed integral with the arm 83. The arm |04 is preferably counter-weighted, as shown at |01, so that movement of the arm about the shaft as its ,axis is facilitated when the thermally sensitive member expands or contracts.

The shaft |05, upon the opposite side of the supporting arm I 06, is adapted to carry an angular magnetic ring member |08, having a plurality of axially extending spaced teeth or pole portions, the teeth of the member |00 being adapted to rotate in alignment with the for` wardly extending edge of the magnetically responsive member 95 carried by the switch.

Upon initial rotation of the shaft |05 due to expansion of the coil |00, under the inuence of the adjustable clamping member |02, the magnetic member I 08 is rotated, and in turn pulls the magnetically responsive arm 95 therewith, rotating the switch member about the bearings 84 and 85, the rotational movement of the switch being limited by the arms ||0 and ||2 formed on the bracket member 83. When the switch has moved to its limiting position, with the magnetically responsive member 95 in engagement withv the arm H0, additional rotation of the shaft |05 in the same direction will result in no further movement of the switch, and the thermally sensitive element |00 can therefore/expand to its entire range of temperature without disturbing the position of the switch after it has been initially moved to one of its circuit controlling positions. However, upon a decrease in temperature, for example, and a consequent contraction of the member |00, the arm |04 is rotated initially in a counter direction, and upon initial rotation, one of the teeth |08 is adapted to attract the arm 95 and to draw the same therewith to move the switch away from position in engagement with the stop H0. Thus, upon decrease in temperature, the switch is again moved into the position in engagement with the stop H2, in which position it is preferably in a circuit closed position for actuating suitable means to raise the temperature of the stack gases.

Upon increase in temperature of these gases, therefore, the velement |00 reverses its direction of rotation, and correspondingly reverses the direction of rotation of the arm |04, moving the member |08 in` a clockwise direction, as viewed in Figure 10. This results in again moving the switch into engagement with the stop |00, where it is in circuit open position, so that the circuit to the heating means is then opened.

'I'hus the arm |04, together with the element I. |00, may rotate for several revolutions, without affecting in any manner the position of the switch, but upon initial reversal of rotation from either of its limiting positions, the arm 04 is adapted to actuate the magnetic piece |08 in such manner as to immediately actuate the switch member. It is believed that the operating characteristics of this particular structure, and their peculiar adaptation to the control of the temperature of stack gases, is therefore clearly disclosed.

It is thus apparent that we have provided a construction wherein a sensitive helical actuating member may be employed for actuating circuit controlling mechanism in accordance with variations in temperature or humidity, and may be adjusted, rstly, for control within a predetermined range of temperature or humidity desired, and secondly, for adjustment to increase or decrease the rate of ,response or actuation of the circuit controlling mechanism per unit of variation of temperature or humidity, by reason of the adjustable clamp which may be engaged with any desired spiral of the helix employed as the sensing member.

Having described our'invention in accordance with the patent statutes, what we claim as new. and desire to secure by Letters Patent is:

L In a device of the class described, a helical element responsive to variations in a characteristic condition of a gas, circuit controlling means operable upon tilting movement, means for supporting and actuating said `circuit controlling means pivoted at one side thereof, and means carried by said actuating means and adapted to be adjustably clamped to a predetermined portion of said helical element for varying the rate at which said actuating means is operated upon unit varia-tion 'in said condition.

2. In a device of the class described, a spirally coiled element responsive to variations in a characteristic condition of a gas, circuit controlling means, means for actuating said circuit controlling means, and means adapted to be clamped to' selected coils of said element and movable therewith, said last-named means engaging said actuating means for varying the operating movement imparted thereto by said element per unit variation in said condition.

A3. In a device of the class described, a spirally coiled element responsive to variations in a. characteristic condition of a gas, circuit controlling means, means for actuating said circuit controlling means, means adjustable longitudinally of said actuating means, and means carried by said adjustable means and having engagement with said element for moving said actuating means upon movement of said element in response to variations in said condition.

4. In combination, a supporting base, a shaft projecting therefrom, a spirally-coiled thermally responsive element mounted on said shaft, means i for angularly adjusting the positionv of said element on said shaft, an actuating member carried bysaid shaft and rotatable independently of said element, means for securing said actuating member to a portion of said element, and circuit controlling means carried by said actuating member. 5. In combination, a thermally-sensitive spirally-coiled element, an actuating bar mounted at one end coaxially with said element and rotatable independently thereof, circuit controlling means carried by said bar, and means engaging the bar and adapted to be clamped to any preselected coil of said spiral for varying the rate of rotation of said bar per unit of movement of said coil in response to temperature changes.

6. In combination, thermally sensitive means,

means for rotating said thermally-sensitive means independently of temperature changes, circuit controlling means, means supporting said circuit controlling means and pivoted at one side of said circuit controlling means, and means for adjustably clamping said supporting means to preselectedportions of said thermally sensitive means.

'7. In combination, thermally sensitive means adapted to expand and contract in accordance with temperature changes, circuit controlling means, means pivoted at one side of and supporting said circuit controlling means, and means for adjustably clamping said supporting means to ,said thermally sensitive means for varying the rate of rotation of said supporting means per unit variation in temperature.

8. A temperature controlling device comprising a coiled thermally-sensitive element, a switch symmetrical about its longitudinal axis and adapted to be tilted axially from one circuit controlling position to another, a bar for supporting said switch intermediate its ends and pivoted at one end"coaxially with said thermally-sensitive element, means slidable longitudinally of said bar and adapted to have frictional engagement with a preselected coil of said element for tilting said bar in accordance with lpredetermined movement of said element, and means for rotatably adjusting the position of said element independently of said bar.

9. In combination, a humidity-responsive element, circuit controlling means, means for controlling actuation of said circuit controlli/ng means, and means engaging said actuation controlling means and adapted to be selectively 'clamped to different portions of said humidityresponsive element to provide for different ratios of movement of said actuating means per unit variation in humidity.

10. In combination, a spirally-coiled humidity responsive element, circuit 'controlling means, means for controlling actuation of said circuit controlling means mounted coaxially of said hunudity-responsive element, and means for rotating said actuation controlling means including means adapted to be adjustably clamped to selected coils of said humidity-responsive means.

l1. In combination, a thermally-sensitive element, a shaft rotatable in accordance with movement of said element, means between said shaft and element for varying the ratio of movement between said shaft and element, circuit controlling means, means for hunting rotation of said circuit closing means, means carried by said shaft for rotating said circuit controlling means from one limiting position to another, said last-named means having movement independently of Said ment, a shaft rotated thereby, circuit controlling means having limited rotational circuit controlling movement, and spaced magnetic means carried by said shaft and 'circuit controlling means for rotating said circuit controlling means upon rotation of said shaft from one circuit controlling position to another independently of mechanical connections therebetween, said shaft having rotational movement past said limiting positions of said 'circuit controlling means, whereby said rotating means rotates said circuit controlling means only during initial rotation of said shaft in either direction.

13. In combination, a thermally-sensitive element, a shaft rotated thereby, a switch mounted to rotate in a limited arc from one circuit controlling position to another, magnetically-responsive means carried by said switch, and magnetic means carried by said shaft for rotating said switch upon initial rotational movement of said shaft, said shaft having additional continuing rotational movement beyond the limiting positions of said switch.

14. In combination, a thermally-sensitive velement, a shaft rotated thereby,a switch rotatable from one limiting circuit controlling position to another, said switch being spaced from and independent of said shaft, and magnetic clutch means operable upon initial rotation of said shaft in either direction for rotating said switch from one limiting position to the other and subsequently independently movable upon continuing rotation of said'shaft in the same direction, said means rotating said switch to its opposite limiting position upon initial rotaton of the shaft in the opposite direction.

15. In a device for controlling a circuit in accordance with variations in moisture content of a `gas, a moisture-responsive member comprising a strip oi' parchment formed into a spiral and treated to expand and contract in accordance with variations in moisture content of said gas, circuit controlling means, and means pivoted at the center of said spiral and secured to a selected coil thereof responsive to movement of said moisture-responsive member for actuating said circuit controlling means.

V16. In combination, a supporting memberl having a projecting stud, a helically coiled member having its inner end secured to said stud and having its outer end free to expand and contract in response to changes in conditions of a gas in contact therewith, an actuating member pivoted coaxially of said stud, means for clamping said actuating member to a predetermined coil of said helix for moving said actuating member about its pivot in response to expansion and contraction of said helix, and a switch member operated by `said movement of said actuating member, the

stress of moving said actuating member being imposed entirely at one side of said stud throughout switching movement in a direction coincident with the direction of expansion and contraction of said helix.

17. In combination, supporting means having a projecting stud, a helix having its inner end secured to said stud and having its outer end i'ree for expansion'and contraction in response to changes in conditions of a surrounding gas, an actuating member pivoted coaxially of said stud and extending radially outwardly therefrom, means for selectively clamping the extending portion Iof said member to a predetermined coil of said helix for movement of said member about 'its pivot upon corresponding movement of said helix, and a switch member supported on said actuating member intermediate the pivoted end and the clamped portion thereof and movable therewith, the stress imparted to said helix during switch operating movement being imposed entirely on one side thereof and remaining substantially constant during all portions of the operating movement.

18. In combination, supporting means having a projectingstud, a helix having its inner end secured to said stud and having its outer end free for expansion and contraction in response to changes in conditions of a surrounding gas, an actuating member pivoted coaxially of said stud and extending radially outwardly therefrom,

means for selectively clamping the extending portion of said member to a predetermined coil of said helix for movement of said member vabout its pivot upon corresponding movement of Said helix, and a switch member supported onv said actuating member intermediate the pivoted end and the clamped portion thereof and movable therewith, the stress imposed by the weight of said actuating member and switch member to said helix remaining substantially constant in direction during all portions of the switch operating movement.

19. In combination, a helix having its inner end fixed in position and having its outer end free to expand and contract in response to changes in condition of afsurrounding gas, a switch member adapted for pivotal movement about the center of said helix from switch open to switch closed position upon corresponding movement of a selected portion of said helix, means for transmitting the stress of operating said switch member to said helix whereby said stress remains substantially constant in direction during all portions of the switch operating movement, and means for clamping said last-named means selectively to any desired coil of said helix.

20. In combination, a thermally responsive helix having'its inner end fixed and its outer end free, an actuating member pivoted coaxially of the inner end of said helix and extending outwardly to one side thereof, means for clamping said member selectively to any desired coil of said helix, and a switch mounted on said member for movement therewith and disposed at one side of said inner end of said helix whereby the stress imposed on said helix to operate said switch is exerted in the same direction on said helix during all portions of the switch operating movement.

21. In combination with apparatus for control of an electric circuit in accordance with variations in a characteristic conditionof a gas, a conditionresponsive element comprising a coil supported at its center and having a free end, a supporting bar pivoted for rotation at the center of said coil andcarrying a switch, circuit controlling means on said bar operable upon tilting movement thereof, and means forv clamping said bar to said coli to transfer movement of said coil in response to variations in said condition into tilting movement' of said bar, said bar in position on one side of its pivot actuating said circuit controlling means reversely to its actuation when rotated to the opposite side ofsaid pivot.

22. In combination, a helix fixedl at its center and expansible Aand contractible in accordance with variations in a characteristic condition of a gas, a bar member pivotally mounted at said center and adapted to be connected to a selected coil of said helix, circuit control means adjustable longitudinally of said bar and normally mounted adjacent the bar pivot, said bar being longitudinally adjustable with respect to its pivot, whereby the major portion of the stress imposed on said bar is transmitted to the bar pivot and the minor portion is transmitted to said helix and exerted in the same direction on said helix during normal operating movement of said helix.

23. In combination, a thermally responsive helix fixed at its center, a bar having one end portion pivotally mounted at said center for free rotation, a mercury switch carried by said bar intermediate its ends and mounted in superposed position thereon when said bar extends laterally to one side of said helix and in dependent position when said bar is rotated substantially and-- means for securing the portion 'of the bar opposite the pivoted end thereof to said coil for transmitting movement of said coil into tilting movement of said bar, whereby said switch in superposed position is actuated by said tilting movement reversely to its actuation in dependent position.

24. Circuit controlling mechanism for use with a helix responsive to a characteristic condition of a'gas, comprising a channel-shaped bar member having longitudinal slots in each of the walls thereof, a switch clip adapted to be adjustably mounted in the slot in the web portion of said member, a mercury switch supported in said clip, a pivot stud extending through the slots in the side walls of said member, friction clip means for pivotally supporting said bar for rotation about said stud in longitudinally adjustable position,

and friction clip means longitudinally slidable on said member and having a portion adapted to frictionally engage a selected coil of said helix, whereby said bar member is tilted about its Divotal support upon actuation of said helix to control actuation of` said switch.

25. In combination, abase, a switch mounted on said base for rotation into and out of circuit closed position, an armature carried by and projecting from said switch, a thermally sensitive coil, a shaft spaced coaxially of said switch and rotated by said coil, and magnetic means carried by said shaft and rotatable therewith for initially moving said armature into circuit limiting positions upon initial rotaton of said shaft in corresponding directions andv independently rotatable wthereafter in the same direction.

sponding directions and independently rotatable thereafter in the same direction, and means for varying the degree of rotation of said shaft per unit movement of said coil.

27. Incombination, a rotatably mounted switch, f

an armature rigidly carried by said switch, means limiting the arc of rotation ofsaid armature between'switch open and switch closed position, a

shaft, magnetic means carried by said shaft for initially attracting said armature from one limiting position to the other upon initial rotation of said shaft in the corresponding direction and thereafter movable independently of said armature in the same direction, and means responsive to a characteristic condition of a gas for rotating said shaft.

28. In combination, a switch having a laterally projecting external armature and movable between limits from switch open position to switch closed position, a thermally responsive coil disposed in a plane at right angles to said armature and rotatable means operable in response to initial expansion or contraction of said coil for attracting said armature from one limiting position to the other, and thereafter movable independently of said armature upon further expansion or contraction of said coil, said means being at all times free of mechanical connection to said armature.

29. In combination, a switch having an armature movable between limits from switch open position to switch closed position, a thermally responsive coil, and means movable in response to initial expansion or contraction of said coil for attracting said armature from one limiting position to the other and thereafter movable independently of said armature upon further expansion or contraction of said coil, said last-named means including a clamping member selectively secured to a predetermined convolution of said' coil whereby movement of said attracting means per unit movement of said coil may be varied.

30. In combination, a rotatably mounted gravity operated mercury switch, an armature rigidly carriedthereby, means limiting the arc oi rotation of saidarmature between switch open and switch closed position, and rotatably mounted magnetic means operable upon rotation in opposite directions for initially attracting said armature from one limiting position to the other upon 

